855 resultados para evolutionary replacement
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The speciose Brazilian Elateridae fauna is characterized by high karyotypic diversity, including one species (Chalcolepidius zonatus Eschscholtz, 1829) with the lowest diploid number within any Coleoptera order. Cytogenetic analysis of Conoderus dimidiatus Germar, 1839, C. scalaris (Germar, 1824,) C. ternarius Germar, 1839, and C. stigmosus Germar, 1839 by standard and differential staining was performed with the aim of establishing mechanisms of karyotypic differentiation in these species. Conoderus dimidiatus, C. scalaris, and C. ternarius have diploid numbers of 2n(male) = 17 and 2n(female) = 18, and a X0/XX sex determination system, similar to that encountered in the majority of Conoderini species. The karyotype of C. stigmosus was characterized by a diploid number of 2n=16 and a neoXY/neoXX sex determination system that was highly differentiated from other species of the genus. Some features of the mitotic and meiotic chromosomes suggest an autosome/ancestral X chromosome fusion as the cause of the neoXY system origin in C. stigmosus. C-banding and silver impregnation techniques showed that the four Conoderus species possess similar chromosomal characteristics to those registered in most Polyphaga species, including pericentromeric C band and autosomal NORs. Triple staining techniques including CMA(3)/DA/DAPI also provided useful information for differentiating these Conoderus species. These techniques revealed unique GC-rich heterochromatin associated with NORs in C. scalaris and C. stigmosus and CMA(3)-heteromorphism in C. scalaris and C. ternarius.
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Gluconeogenic activity and kinetic parameters of glucose metabolism were estimated during the different phases of prolonged food deprivation in quails. Gluconeogenic activity, estimated from the rate of increase of incorporation of (HCO3-)-C-14 into circulating glucose, was significantly higher in fasted quails than in fed birds, whatever the period of food deprivation. However, gluconeogenic activity during phase II, although higher than in the fed state, was significantly lower than in quails fasted for 2 days (phase I) or in those on the final (phase III) period of starvation. Gluconeogenic activity did not differ significantly in birds from phases I and III. Rates of glucose replacement, estimated with [6-H-3]-glucose, were very high (20.5 mg . kg(-1). min(-1)) in fed quails and were markedly reduced (to about 42% of fed values) by fasting, no difference being observed between quails fasted for 2 and 5 days. Because of the poor condition of the birds, glucose replacement rates could not be measured during phase III. The present data are the first to provide direct evidence for the changes in gluconeogenesis which occur during prolonged food deprivation.
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The 3' terminal genomic region of a potyvirus causing mosaic disease in several Crotalaria species has been cloned and sequenced. Comparisons of the nucleotide and deduced amino acid (aa) sequences of the cloned cDNA with those from other potyviruses show that the Crotalaria-infecting virus (designated Crotalaria mosaic virus; CrMV) is closely related to Cowpea aphid-borne mosaic virus (CABMV). Maximum identity (95.4%) at the coat protein (CP) aa level was observed between CrMV and a Brazilian strain of CABMV. Phylogenetic analyses derived from the sequence alignments of the CP and 3' untranslated region confirmed the identification of CrMV as a strain of CABMV and the name CABMV-Cr is suggested.
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The procedure for formaldehyde analysis recommended by the National Institute for Occupational Safety and Health (NIOSH) is the Chromotropic acid spectrophotometric method, which is the one that uses concentrated sulphuric acid. In the present study the oxidation step associated with the aforementioned method for formaldehyde determination was investigated. Experimental evidence has been obtained indicating that when concentrated H2SO4 (18 mol l(-1)) is used (as in the NIOSH procedure) that acid is the oxidizing agent. on the other hand, oxidation through dissolved oxygen takes place when concentrated H2SO4 is replaced by concentrated hydrochloric (12 mol l(-1)) and phosphoric (14.7 mol l(-1)) acids as well as by diluted H2SO4 (9.4 mol l(-1)). Based on investigations concerning the oxidation step, a modified procedure was devised, in which the use of the potentially hazardous and corrosive concentrated H2SO4 was eliminated and advantageously replaced by a less harmful mixture of HCl and H2O2. (C) 2003 Elsevier B.V. B.V. All rights reserved.
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Objective: To evaluate the effects of isoflavones on vasomotor symptoms and blood lipids in postmenopausal women with contraindication for conventional hormone replacement therapy (HRT). Methods: This prospective, double-blind and placebo-controlled study included 50 postmenopausal women randomly divided into two groups: 25 women on soy germ isoflavones (60 mg per day, capsules) and 25 women on placebo. Inclusion criteria included: non-vegetarian, non-asian women whose last menstruation dated at least 12 months prior to the beginning of the study, With FSH > 40 mIU/ml, hot flushes and contraindication for HRT, not using tamoxifen or antibiotic and no disease of the gastrointestinal tract. For 6 months, the Kupperman menopausal index (KMI), the vaginal cytological maturation value (MV) and both hormonal and lipid profiles were assessed. The t-test and analysis of variance (ANOVA) were employed to compare the two groups. Results: In both groups, a decreased KI rate was observed. However, isoflavone was significantly superior to placebo in reducing hot flushes (44% versus 10%, respectively) (P < 0.05). After 6 months, the isoflavone group showed increased estradiol levels with unchanged FSH, LH, and vaginal cytology, and a reduction of 11.8% in LDL and an increase of 27.3% in HDL (P < 0.05). In the placebo group, just a reduction in MV was observed after 6 months (P < 0.05). Conclusions: Soy germ isoflavone exerted favorable effects on vasomotor symptoms and lipid profile, showing itself to be an interesting alternative therapy for the postmenopausal women with contraindication for conventional HRT. (C) 2003 Elsevier B.V.. All rights reserved.
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Numerous nymphoid reproductives were found in three field nests of Armitermes euamignathus collected in Brazil. We report here a morphological description and a biometric study of these individuals. Nymphoid replacements displayed narrow wing buds when compared with those present in nymphs from the three last instars. Thorax morphology of the nymphoids was similar to the penultimate nymphal instar (N4) or to the ultimate nymphal instar (N5), and their origin from these instars of nymphs is discussed. All the nymphoids had eyes, ocelli, and 15 antennal segments. The nymphoid females from nest 1 had different grades of physogastry and royal fat body. The nymphoid females from nests 2 and 3, the nymphoid males from all nests, and the primary king from nests 2 acid 3 had a common fat body, which is similar to that present in alates. The ovaries and the testes of nymphoids were fully mature and the corpora allata larger than those in imagoes. The mandibular glands were also enlarged in nymphoids but the tergal glands were absent. (C) 1999 Wiley-Liss, Inc.
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Theory recently developed to construct confidence regions based on the parametric bootstrap is applied to add inferential information to graphical displays of sample centroids in canonical variate analysis. Problems of morphometric differentiation among subspecies and species are addressed using numerical resampling procedures.
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The habitat of the mycelial saprobic form of Paracoccidio ides brasiliensis, which produces the infectious propagula, has not been determined and has proven difficult for mycologists to describe. The fungus has been rarely isolated from the environment, the disease has a prolonged latency period and no outbreaks have been reported. These facts have precluded the adoption of preventive measures to avoid infection. The confirmation of natural infections in nine-banded armadillos (Dasypus novemcinctus) with P. brasiliensis, in high frequency and wide geographic distribution, has opened new avenues for the study and understanding of its ecology. Armadillos belong to the order Xenarthra, which has existed in South America ever since the Paleocene Era (65 million years ago), when the South American subcontinent was still a detached land, before the consolidation of what is now known as the American continent. on the other hand, strong molecular evidence suggests that P. brasiliensis and other dimorphic pathogenic fungi - such as Blastomyces dermatitidis, Coccidioides immitis and Histoplasma capsulatum - belong to the family Onygenaceae sensu Into (order Onygenales, Ascomycota), which appeared around 150 million years ago.P. brasiliensis ecology and relation to its human host are probably linked to the fungal evolutionary past, especially its long coexistence with and adaptation to animal hosts other than Homo sapiens, of earlier origin. Instead of being a blind alley, the meaning of parasitism for dimorphic pathogenic fungi should be considered as an open two-way avenue, in which the fungus may return to the environment, therefore contributing to preserve its teleomorphic (sexual) and anamorphic (asexual) forms in a defined and protected natural habitat. (c) 2006 Elsevier B.V. All rights reserved.
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Haemoglobin, the 'honorary enzyme' [Brunori (1999), Trends Biochem. Sci. 24, 158-161], constitutes a prime prototype for allosteric models. Here, the crystallization and preliminary X-ray analysis of haemoglobin I from the South American fish Brycon cephalus are reported. X-ray diffraction data have been collected to 2.5 Angstrom resolution using synchrotron radiation (LNLS). Crystals were determined to belong to the space group P6(1)22 and preliminary structural analysis revealed the presence of one dimer (alpha beta) in the asymmetric unit. The structure was determined using standard molecular-replacement techniques.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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In this study, the occurrence of Othonella araguaiana Mendes, a rare bivalve species is reported for the first time in the Pinzonella illusa biozone, Middle Permian Corumbatai Formation, in the State of São Paulo. This species was originally described in coeval rocks of the Estrada Nova Formation (= Corumbatai) from the Alto Araguaia and Alto Garcas regions, State of Mato Grosso. The specimens of O. araguaiana were found in the base of a bioclastic sandstone bed, a proximal tempestite, in the middle of the Corumbatai Formation, in the city of Rio Claro, São Paulo State. The silicified shells and internal molds are well preserved, showing impressions of muscle scars and other internal anatomic characters (e.g., hinge), never illustrated by previous authors. In his original description, Mendes (1963) called attention to the similarity between O. araguaiana and Terraia aequilateralis, a common veneroid of the Corumbatai Formation. Conversely, Runnegar and Newell (1971) suggested that O. araguaiana belongs to Megadesmidae, being a junior synonym of Plesiocyprinella carinata (the commonest megadesmid of the Passa Dois Group). Our study indicates that O. araguaiana is indeed a megadesmid, but is distinct from the P. carinata. The new occurrence of O. araguaiana demonstrates that a) the paleobiogeographic distribution of this species is wider than previously thought (that it was restricted to the northern part of Parana Basin, Mato Grosso State); b) the molluscan fauna of the Corumbatai Formation (P. illusa biozone) in the State of São Paulo is more diverse and dominated by megadesmids; and c) the composition of the molluscan fauna of the Corumbatai Formation in Alto GarYas, State of Mato Grosso, is essentially the same as that of the P. illusa biozone of the eastern margin of the Parana Basin.